You're thinking of AGPL for requiring source distribution when offering a service over a network. IANAL but I don't believe GPLv3 changes anything over GPLv2 i

You're thinking of AGPL for requiring source distribution when offering a service over a network. IANAL but I don't believe GPLv3 changes anything over GPLv2 in this case, although it does tighten up some loopholes in v2 over what does and does not qualify as "distribution" (although in all cases the end user is still sent the software to run on their hardware, not just the results of the software.)